Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS5360610 A
Publication typeGrant
Application numberUS 08/033,309
Publication dateNov 1, 1994
Filing dateMar 15, 1993
Priority dateMay 16, 1990
Fee statusPaid
Also published asDE69133136D1, DE69133136T2, EP0528978A1, EP0528978A4, EP0528978B1, WO1991017772A1
Publication number033309, 08033309, US 5360610 A, US 5360610A, US-A-5360610, US5360610 A, US5360610A
InventorsThomas R. Tice, Deborah L. Dillon, David W. Mason, Amanda McRae-McFarlane, Annica B. Dahlstrom
Original AssigneeSouthern Research Institute
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method for stimulating nerve fiber growth
US 5360610 A
Abstract
The present invention relates to polymeric microspheres as injectable, drug-delivery systems for use to deliver bioactive agents to sites within the central nervous system, and for the stimulation of nerve fiber growth by implanting such microspheres within the central nervous system of a patient.
Images(6)
Previous page
Next page
Claims(11)
We claim:
1. A method for eliciting neural fiber growth within the central nervous system which comprises implanting within the central nervous system a neuro-active neural fiber growth eliciting molecule encapsulated within a microsphere comprising the copolymer of poly(lactide-co-glycolide) or a homopolymer of polylactide or polyglycolide.
2. A method according to claim 1 wherein the microsphere is selected from a group consisting of particles having the neuro-active molecule centrally located within a polymeric membrane, or an matrix structure of neuro-active molecule and polymeric excipient.
3. A method according to claim 1 wherein the microspheres are spherical particles of from about 5 to about 45 μm in diameter.
4. A method according to claim 1 wherein the neuro-active molecule is selected from the group consisting of neurotransmitters, neuropeptides, dopamine, dopamine precursors, norepinephrine, epinephrine, serotonin, substance P, somatostatin, nerve growth factor, angiotensin II, and gamma aminobutyric acid.
5. A method according to claim 4 wherein the neuro-active molecule is dopamine, dopamine precursors, norepinephrine, epinephrine and mixtures thereof.
6. A method according to claim 1 wherein the neuro-active molecule is dopamine or a dopamine precursor.
7. A method according to claim 1 wherein the amount of neuro-active molecule is from about 10 to 80 per cent of the total weight of the microsphere.
8. A method according to claim 1 wherein implantation is by injection and wherein placement is within the medial axis of the central nervous system.
9. A method according to claim 1 wherein the microsphere comprises the copolymer of poly(lactide-co-glycolide).
10. A method according to claim 1 wherein the microsphere comprises the homopolymer of polylactide.
11. A method according to claim 1 wherein the microsphere comprises the homopolymer of polyglycolide.
Description

This application is a continuation of Ser. No. 535,383 filed May 16, 1990, now abandoned.

It has long been recognized that delivering a drug to its therapeutic site of action within the central nervous system can be a very difficult task because of the numerous chemical and physical barriers which must be overcome in order for such delivery to be successful. A number of methods have been designed to overcome some of these barriers to central nervous system drug delivery as, for instance, the use of liposomes to surmount the blood-brain barrier. However, the disadvantages of a liposome delivery system, including low drug loadings, short duration of action, limited ways to manipulate the rate of drug release, poor storage stability, and problems with scale-up, have precluded the use of such a system. Another method to overcome some of the barriers to central nervous system drug delivery consists of chemically modifying the active drug to a form, called a prodrug, that is capable of crossing the blood-brain barrier, and once across this barrier the prodrug reverts to its active form. One example of such a prodrug delivery system consists of the neurotransmitter dopamine attached to a molecular mask derived from the fat-soluble vitamin niacin. The modified dopamine is taken up into the brain where it is then slowly stripped from its prodrug mask to yield free dopamine.

The most common method to surmount some of the physical barriers preventing drug delivery to the central nervous system has been through the use of pumps. A variety of pumps have been designed to deliver drugs from an externally worn reservoir through a small tube into the central nervous system. Although such pump delivery systems can be externally controlled to a certain degree, the potential for infection directly within the central nervous system is great and the exact site of action of the drug within the central nervous system is largely beyond control.

To be successful, it does not suffice just to deliver the drug within the central nervous system. The drug must be delivered to the intended site of action, at the required rate of administration, and in the proper therapeutic dose. Commercially, the Alzet osmotic mini-pump has become an acceptable, very useful, and successful means of delivering drugs at a controlled rate and dose over extended periods within the central nervous system. However, adapting this device to deliver the desired drug to discrete brain nuclei presents vast difficulties such as implanting cannulas directly within the designated brain regions.

Still another technique that has been developed to deliver neuro-active agents, such as neurotransmitters, to the central nervous system is with the use of neural transplants. Viable neuronal tissue can be implanted directly within discrete brain nuclei. The duration of substance delivery from the transplanted tissue does not present a problem because implanted tissue may survive for a long time in the host's central nervous system. This technique surmounts a number of obstacles cited above, however, despite claims that neuronal grafts from fetal dopamine cells exhibit some of the autoregulatory feedback proterties that are normally found in intact dopamine neuronal systems, the exact rate at which the neurotransmitters are delivered from neuronal transplants at their site of action can not be predetermined.

In 1817, James Parkinson described a disease which he termed "shaking palsy". This condition is presently known as Parkinson's disease and occurs in the middle-aged and elderly. While its onset is insidious, often beginning with tremor in one hand followed by increasing bradykinesia and rigidity, it is slowly progressive and may become incapacitating after several years. In idiopathic Parkinson's disease, there is usually a loss of cells in the substantia nigra, locus ceruleus and other pigmented neurons, and a decrease of dopamine content in axon terminals of cells projecting from the substantia nigra to the caudate nucleus and putamen commonly referred to as the nigrostriatal pathway.

Some symptoms of Parkinson's disease can be treated by the administration of L-3,4-dihydroxyphenylalanine (levodopa or L-dopa). L-dopa, the metabolic precursor of dopamine, is used for replacement therapy because dopamine itself does not cross the blood-brain barrier. However, it must be given in large doses of 3 to 15 grams per day because much of the drug is metabolized before it reaches the site of action in the brain. Alternatively, it is often given in combination with a dopa decarboxylase inhibitor, such as carbidopa, which prevents the metabolism of L-dopa until it crosses the blood-brain barrier. Its greatest effect is on bradykinesic symptoms. After about five years of treatment, side effects develop and the treatment becomes less and less effective even with increasing doses of the drug. These problems have raised the question of whether or not it would be possible to replace the lost dopamine by other means which would deliver the drug to its therapeutic site of action within the central nervous system.

Even though these approaches are well documented for experimental animal models, their use as therapy for neurodegenerative disorders such as Parkinson's disease present a number of practical as well as ethical considerations. Not only is the use of human aborted fetal tissue a controversial issue, but this technique involves complicated surgical procedures. Furthermore, although clinical trials of adrenal and fetal tissue implants in Parkinsonian patients are being conducted, the mechanism and long-term efficacy of tissue transplants within the nervous system remain unclear and is still a matter of medical debate. The best theoretical approach for treatment of such central nervous system pathologies continues to be one which would deliver the biologically active agent directly to the damaged region of the central nervous system.

Although a number of different methods have been proposed and are presently being utilized for the delivery of pharmaceutically active compounds to the central nervous system, there are sufficient disadvantages to each method that the need for delivering biologically active substances to the central nervous system still exists. The present invention addresses this need in a unique manner.

The discovery that a unilateral lesion of the nigrostriatal pathway with the neurotoxin 6-hydroxy-dopamine produced an asymmetry of movement and posture in the rat, provided an animal model for Parkinson's disease. This asymmetry of movement is employed in the rotometer model developed to measure rotational behavior induced by drugs that interfere with dopamine neurotransmission such as apomorphine. The characteristic apomorphine induced rotational behavior is only observed in animals with a 95% reduction of dopamine levels in the striatum, and replacement dopamine in this tissue either by transplants of fetal dopamine producing cells or adrenal medullary tissue results in significant decreases in apomorphine induced rotational behavior.

Broadly defined, the present invention relates, in part, to microspheres that have been developed as injectable, drug-delivery systems in which bioactive agents are contained within a compatible biodegradable polymer. As used with regard to the present invention, the term microsphere includes microcapsules, nanocapsules and nanospheres.

Microcapsules and microspheres are conventionally free flowing powders consisting of spherical particles of 2 millimeters or less in diameter, usually 500 microns or less in diameter. Particles less than 1 micron are conventionally referred to as nanocapsules or nanospheres. For the most part, the difference between a microcapsule and a nanocapsule, or a microsphere and a nanosphere, is size; generally there is little, if any, difference between the internal structure of the two.

As used in the present invention, the microcapsule, or nanocapsule, has its encapsulated material (in the present invention this is a bioactive agent or drug) centrally located within a unique membrane. This membrane may be termed a wall-forming polymeric material. Because of their internal structure, permeable microcapsules designed for controlled-release applications release their agent at a constant rate (called a "zero order" rate of release). Thus, as used in the present invention, microcapsules include microparticles in general which comprise a central core surrounded by a polymeric membrane.

In addition, microspheres encompass "monolithic" and similar particles in which the bioactive agent is dispersed throughout the particle; that is, the internal structure is a matrix of the bioactive agent and a polymer excipient. Usually such particles release their bioactive agents at a declining rate (a "first order" rate of release), however such particles may be designed to release internal agents within the matrix at a near zero order rate. Thus, as used in the present invention, microspheres also include microparticles in general which have an internal structure comprising a matrix of bioactive agent and polymer excipient.

The specific polymer employed in the present invention, poly (lactide-co-glycolide), has a number of advantages which render it unique to the method of the present invention. An advantage of this polymer is that it is similar to materials used in the manufacture of present-day resorable sutures. Another advantage is that this material is biocompatible with the tissues of the CNS. Still another advantage is that this material is biodegradable within the tissues of the central nervous system without producing any toxic byproducts of degradation. A still further advantage of this material is the ability to modify the duration of drug release by manipulating the polymer's biodegradation kinetics, i.e. by modifying the ratio of lactide and glycolide in the polymer; this is particularly important because of the ability to deliver neuro-active molecules to specific regions of the brain at a controlled rate over a predetermined period of time is a more effective and desirable therapy over current procedures for administration. Microspheres made with this polymer serve two functions: they protect drugs from degradation and they release drugs at a controlled rate over a predesired time. Although polymers have been previously reported for use in the microencapsulation of drugs, the physical, chemical and medical parameters of the microencapsulating polymer for neuro-active molecules to be used in central nervous system implantation technique according to the present invention are narrow; there is no general equivalency among polymers which allows a polymer previously used for encapsulation of drugs to be freely exchanged for the polymers used to encapsulate neuro-active molecules for drug delivery to the central nervous system according to the present invention. This is especially true when the site of utilization is the central nervous system. Although the specifically named polymer according to the present invention meets the criteria necessary for implantation within the central nervous system, other biocompatible, biodegradable polymers and copolymers having advantages which are similar to those named advantages of poly(lactide-co-glycolide) may be substituted.

Results obtained from a number of studies indicate that implantation of these neuro-active agent containing microspheres provides a feasible method for prolonged release of the agent into the central nervous system. Moreover, the data obtained from studies involving dopamine as the encapsulated agent indicate that dopamine microsphere preparations have the potential of being employed as a source of transmitter replacement allowing diffusion of the microencapsulated dopamine directly into the central nervous system at a controlled rate for pre-determined periods of time assuring functional significance and at the same time remaining compatible with the central nervous system tissue. However, most surprisingly, the data indicate that microencapsulated dopamine injected into specific regions of the brain has the heretofore unreported ability to cause growth of nerve fibers. Thus, the method of placing the microencapsulated neuro-active agents, manufactured in accordance with one aspect of the present invention, has the potential of promoting the growth of those neural elements which are responsible for the production of endogenous dopamine within the central nervous system. Once growth has taken place and the neural fiber elements have matured and stabilized within their environment, they will continue to produce and release dopamine within the central nervous system thereby providing for the first time a potential cure for Parkinson's disease.

Among the neuro-active molecules or agents which may be microencapsulated and used according to the present invention are neurotransmitters, neuropeptides, and neurotrophic factors including such agents as norepinephrine, epinephrine, serotonin, dopamine, substance P, somatostatin, nerve growth factor, angiotensin II, and gamma aminobutyric acid.

Among the neurological diseases which may be treated microencapsulated neuro-active molecules being placed directly within the tissues of the central nervous system are Parkinson's disease, Huntington's Chorea, Alzheimer's disease, Epilepsy, and Tardive dyskinesia. Depending upon the disease to be treated, it may be advantageous to provide more than one microencapsulated neurotransmitter, neuropeptide and neuronotrophic factor to the central nervous system. For example, as dopamine, cholecystokinin, and epidermal and basic fibroblast growth factors may all be involved in Parkinson's disease, ultimately it may be advantageous when presented with a patient having the disease to provide a mixture of microencapsules containing two, three, or all four neural-active molecules to the central nervous system.

In order to provide a more complete description and provide a greater understanding of the various aspects of the present invention, reference is made to the following examples.

EXAMPLE 1 Preparation of Dopamine Microspheres

A weight % polymer solution was prepared by dissolving 2 g of 50:50 poly(DL-lactide-co-glycolide) ("DL-PLG") in 198 g of dichloromethane (The DL-PLG had an inherent viscosity of 1.27 dL/g.). Two grams of dopamine (3-hydroxytyramine hydrochloride) were suspended in the polymer solution by homogenization. The dopamine suspension was then poured into 300 mL resin kettle and stirred at 3500 rpm with a 1.5 inch Teflon impeller. Silicone oil (350 cs) was pumped into the resin kettle at a rate of 2 mL per min. After approximately 50 mL of oil was added, the contents of the resin kettle were poured into 3.5 L of heptane. The heptane was stirred at 900 rpm with a 2.5 inch stainless steel impeller. After 0.5 h of stirring, the dopamine microsphere suspension was poured through a stainless steel sieve with 45 μm openings to remove microspheres larger than 45 μm in diameter. Microshperes less than 45 μm in diameter were collected on a fritted glass filter funnel and dried at room temperature in a vacuum oven for 48 h. The dopamine microspheres were then collected in tared glass scintillation vials and stored under desiccant at 4 C.

Dopamine was encapsulated in two types of copolymer excipients made in accordance with Example 1. One copoylmer had a 50:50 mole ratio of lactide to glycolide and the other copolymer had a 65:35 mole ratio. In view of the higher lactide content of the 65:35 copolymer, this copolymer will take longer to biodegrade than the 50:50 copolymer. Thus, the delivery time of the 65:35 copolymer can be longer than the delivery time of the 50:50 copolymer. Additional variations of the actual proportions of lactide and glycolide in the copolymer and the copolymer morphology may be manufactured to more or less custom adjust the rate and amount of neuro-active molecule being released into the central nervous system.

The final microspheres are free-flowing powders consisting of spherical particles approximately 5 to 45 μm in diameter. These microspheres can easily be suspended in aqueous vehicles and injected through conventional hypodermic needles. Although the amount of dopamine contained in each microsphere may vary, the microspheres manufactured and used in the following example consisted of about 40% (by weight) dopamine and of about 60 % (by weight) of the poly(DL-lactide-co-glycolide). When used as a therapeutic, the microspheres may contain from about 10% to about 80% [by weight] dopamine). In vitro diffusion tests of these microspheres showed that most of the dopamine was released into deionized water within 30 minutes. Prior to injection, the microspheres are sterilized with, preferably, gamma radiation.

EXAMPLE 2 Administration of Microspheres

Microencapsulated dopamine was formulated (15 mg of 50:50 microcapsulated dopamine in 50 μL saline or 30 mg of 65:35 microencapsulated dopamine in 50 μL of saline) for implantation into previously treated rat models.

Male Sprague Dawley rats were unilaterally lesioned in the ascending median forebrain bundle of monoamine neurons using the neurotoxin 6-hydroxy-dopamine. Two weeks later, the animals were challenged with apomorphine (0.1 mg/kg SC) and rotational responses were monitored in a computerized rotometer set-up. Only rats in which the dopamine denervation has been successful will display strong contralateral rotation to apomorphine challenge. Therefore, animals responding to apomorphine with less than 400 contralateral rotations per 60 minutes during the first two weeks of testing were eliminated from the study. Testing of positive responders was then continued on a weekly basis using apomorphine.

Once the animals reached a stable rotational baseline level to dopamine agonist challenge, they were stereotaxically injected under light ether anesthesia with a suspension of dopamine microspheres. Dopamine/50:50 DL-PLG microspheres (15 mg microspheres/50 μL saline) were injected in 3 μL implants into the striatum. Dopamine/65:35 DL-DPG microspheres were correspondingly implanted (30 mg microspheres/50 μL saline) in the striatum. Based upon experience, it was expected that the 65:35 DL-PLG microspheres would biodegrade completely in about 12 weeks, and the 50:50 DL-PLG microspheres would do so in about 6 weeks. Thus, to ensure similar doses of dopamine would be released per unit time, the amount of dopamine in the 50:50 DL-PLG microspheres was half that of the 65:35 DL-PLG microspheres. Control rats received similar implants with dopamine-free microspheres. Standard Hamilton syringes (50 μL) connected by polyethylene tubing to stainless steel injection cannulae were used for the injections. Upon completion of the injection, the cannula were left in situ for an additional 60 sec before being slowly retracted and the skin wound closed. Starting 1 to 3 days after implantation of the dopamine microspheres, the animals were repeatedly tested for dopamine agonist-induced rotation at various intervals over an 8 week period.

Thirty to forty minutes after intrastriatal implantation of the microencapsulated dopamine, those rats receiving the dopamine/50:50 DL-PLG microsphere implantation exhibited contralateral rotations with an amplitude similar to that of a previous test dose of apomorphine but with longer duration. Rats receiving the dopamine/65:35 DL-PLG microsphere implantation displayed a somewhat more protracted response to the implantation, however once begun, these animals have a peak rotation amplitude similar to that of those receiving the dopamine/50:50 DL-PLG microspheres. Rats receiving a control charge of empty microspheres did not display rotational behavior. Histological evaluations made upon sacrificed animals indicate that the injection of a suspension of microspheres according to the present invention into the rat brain is an acceptable means of delivering dopamine to the central nervous system; only minimal damage to the surrounding tissue and minimal glial reaction was noted following injection. Thus, there is little concern that a morphological barrier exists which would prevent the diffusion of dopamine into the targeted region.

Thus, we have confirmed our original belief that the specific polymeric microspheres according to the present invention provide a unique and acceptable means to introduce neuro-active molecules into the central nervous system.

The most outstanding result of delivering dopamine to the central nervous system utilizing the method and microspheres of the present invention is finding the presence of dopamine immunoreactive fibers growing towards the dopamine microspheres. This is not seen in control (those not containing dopamine) microsphere implantation. The ability of implanted dopamine microspheres manufactured and implanted according to the present invention to elicit neuronal sprouting may provide not only a treatment for neurologically debilitating diseases such as Parkinson's disease, but a cure as well.

As part of ongoing research into the direct delivery of neuro-active molecules to the brain, an antibody to dopamine showing no cross reactivity with other neurotransmitter systems (such as norepinephrine, serotonin or gamma amino butyric acid) when utilized in ELISA test systems was developed. This antibody has been shown in both ELISA and immunocytochemical test systems to recognize dopamine and is a reliable means of demonstrating fiber outgrowth in the rat brain as depicted in the following example:

EXAMPLE 3 Fiber Formation

The immunogen complex to obtain antibodies against dopamine is prepared by coupling the hapten to glutaraldehyde (G) and bovine serum albumin (BSA). Rabbits are then immunized with this immunogen. Antibodies directed toward dopamine were detected 50 days following the immunization schedule of 4 injections at 10 day intervals. To eliminate antibodies that are produced against BSA-G, the dopamine antibody was adsorbed by affinity chromatography. In order to visualize dopamine within brain tissue, the rats were perfused with gluteraldehyde thereby fixing dopamine and tissue proteins. Thus, because the antibody is directed against dopamine-gluteraldehyde and a protein, the antibody will recognize this complex within the brain. Rats were deeply anesthetized with sodium pentobarbital and perfused through the aorta with a mixture composed of 5% glutaraldehyde and an anti-oxidant to prevent the rapid release of dopamine from the brain tissue. After the rats were perfused with this mixture, the brains were removed and allowed to equilibrate overnight in 10% sucrose solution. The brains were then frozen, sectioned, and the sections incubated with anti-dopamine antiserum for 24 hours. The following day the sections were reacted with goat anti-rabbit biotin IgG which recognizes the antiserum produced in the rabbit. Following this, the sections were incubated with avidin biotin-peroxidase complex which recognizes the fixed biotin molecules. The peroxidase was then reacted with a classical chromatogen for this type of reaction, 3,3 diaminobenzidine, and the reaction enhanced by the addition of ammonium nickel sulphate giving a purple stain to the antibody reaction. Therefore, the presence of dopamine in the brain tissue is visualized as a purple deposit in the tissue; if dopamine is not present in the tissue, the tissue remains unstained.

As noted previously, the implantation of control microspheres did not modify the apomorphine-induced rotational responses in the rat, indicating at least a 95% decrease of dopamine in the central nervous system. Microscopic observations of the tissues following staining in accordance with Example 3 confirmed that dopamine was absent in the striatum of the rats receiving the control microspheres, that is the brain tissue remained unstained. However, in animals that received the dopamine microspheres and displayed a continued decrease in apomorphine rotational behavior, microscopic observations indicated dopamine was present both in the microcapsules and the tissue. As noted previously, numerous fine fiber extensions were seen growing towards the implanted microspheres, and dopamine was present in these fibers. These findings indicate that dopamine nerve fibers were growing within the host animals' central nervous system, a phenomena heretofore unreported. The implanted dopamine containing microspheres apparently have the ability to elicit growth of nerve fibers from the base of the brain toward the microspheres. These fibers were present in all animals which displayed a continued decrease in the number of apomorphine induced rotations which appears to be due to a release of dopamine from the microspheres as well as the growing dopamine fibers within the host's central nervous system. Similar observations were noted for both the 50:50 DL-PLG and 65:35 DL-PLG dopamine microspheres.

The anatomical placement of the dopamine microspheres appears to be important for both fiber growth and functional recuperation. One rat striatum is about 3 mm in width and 4 mm in depth. Dopamine fibers growing from the base of the brain are mainly located in the more medially ventral portion of the striatum in comparison to the extreme lateral portion of this nucleus. Placing dopamine microspheres at the base of the brain stimulates growth of these particular fibers. It appears that the diffusion of dopamine from these microspheres placed in this location reaches these fibers and they grow towards the microspheres. The lateral placement of dopamine containing microspheres therefore appears too distant to allow dopamine diffused from the microspheres to influence these fibers.

Immunocytochemical investigations with an antibody to growth associated protein, a protein associated with systems undergoing fiber growth, indicated the growing fibers were reactive to this protein, an indication that the nerve fibers are undergoing a fiber growth. Injection of fluorogold within the denervated striatum 2 weeks after implantation of dopamine microspheres indicates retrograde labelling of neurons within the ventral tegmentum region, suggesting that the dopamine microspheres trigger the growth of dopamine fibers.

Another observation of growth of fibers has been made when the microspheres were implanted into the striatum of a genetic mouse model. The Weaver mouse strain carries an autosomal recessive mutation and provides investigators a means to investigate fiber growth following dopamine microsphere implantation into a brain region where dopamine is "naturally" depleted. These genetically aberrant mice are severely depleted of their brain dopamine. The abnormality is particularly marked in the nigrostriatal dopamine tract while the mesolimbic dopamine neurons appear less affected. Implanting dopamine microspheres within the striatum of this mouse model equally stimulates the growth of dopamine fibers in the striatum probably emanating from the genetically unaffected dopamine system.

Thus, while we have illustrated and described the preferred embodiment of my invention, it is to be understood that this invention is capable of variation and modification, and we therefore do not wish or intend to be limited to the precise terms set forth, but desire and intend to avail ourselves of such changes and modifications which may be made for adapting the present invention to various usages and conditions. Accordingly, such changes and modifications are properly intended to be within the full range of equivalents, and therefore within the purview of the following claims. The terms and expressions which have been employed in the foregoing specification are used as terms of description and not of limitation, and thus there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described, or portions thereof; the scope of the invention being defined and limited only by the claims which follow.

Having thus described our invention and the manner and process of making and using it in such full, clear, concise, and exact terms so as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same,

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4883666 *Apr 29, 1987Nov 28, 1989Massachusetts Institute Of TechnologyControlled drug delivery system for treatment of neural disorders
US4962091 *May 23, 1986Oct 9, 1990Syntex (U.S.A.) Inc.Controlled release of macromolecular polypeptides
US4994281 *Nov 10, 1987Feb 19, 1991Sanraku IncorporatedPolylactic acid microspheres and process for producing the same
JPS6048923A * Title not available
Non-Patent Citations
Reference
1"Process for encapsulation of bioactive substances in polymers", Kormean et al., Pharmaceuticals 63-6, 1990 (Abstract).
2"Prolonged Delivery of Peptides by Microcapsules", Maulding J. Controlled Release, 6, 167-76, 1987 (Abstract).
3 *Process for encapsulation of bioactive substances in polymers , Kormean et al., Pharmaceuticals 63 6, 1990 (Abstract).
4 *Prolonged Delivery of Peptides by Microcapsules , Maulding J. Controlled Release, 6, 167 76, 1987 (Abstract).
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5573528 *Jun 5, 1995Nov 12, 1996Brown University Research FoundationImplanting devices for the focal release of neuroinhibitory compounds
US5591445 *Oct 10, 1995Jan 7, 1997Regents Of The University Of MinnesotaFor stimulating peristaltic contractions of intestines, barium chloride or neurotransmitter dispersed in silicone matrix
US5604198 *May 12, 1994Feb 18, 1997Poduslo; Joseph F.Parenterally administering conjugate consisting of neurologically active compound conjugated to carrier molecule permeable across said barrier
US5750103 *Jun 2, 1995May 12, 1998The New York University Medical CenterMethod for transplanting cells into the brain and therapeutic uses therefor
US6123956 *Jul 9, 1998Sep 26, 2000Keith BakerMethods for universally distributing therapeutic agents to the brain
US6217911Jul 5, 1996Apr 17, 2001The United States Of America As Represented By The Secretary Of The ArmyBlend containing poly(lactide/glycolide) polymer
US6241981Sep 16, 1997Jun 5, 2001Purdue Research FoundationComposition and method for repairing neurological tissue
US6264943Dec 10, 1999Jul 24, 2001New York UniversityParkinson's disease
US6303134Aug 28, 1997Oct 16, 2001Advanced Research And Technology Institute, Inc.Selecting in situ locus in central nervous system which includes agonist receptors and heterologous receptors that are coupled to common g-proteins; seteotaxially delivering biodegradable, non-spherical polymeric microstructure
US6410056May 22, 1995Jun 25, 2002The United States Of America As Represented By The Secretary Of The ArmyPolylactide-glycolide copolymer
US6447796Aug 21, 1997Sep 10, 2002The United States Of America As Represented By The Secretary Of The ArmySustained release hydrophobic bioactive PLGA microspheres
US6455526Dec 7, 1999Sep 24, 2002Aventis Pharmaceuticals, Inc.Biodegradable polymer encapsulated pharmaceutical compositions and method for preparing the same
US6488952 *Aug 28, 2001Dec 3, 2002John P. KennedySemisolid therapeutic delivery system and combination semisolid, multiparticulate, therapeutic delivery system
US6491939Jul 2, 2001Dec 10, 2002Advanced Research And Technology Institute, Inc.Pharmacotherapeutic process and composition for central nervous system disorders
US6517859 *Jun 29, 1994Feb 11, 2003Southern Research InstituteInjectable, drug delivery vehicles; controlled release of bioactive agents to sites within the central nervous system; dopamine, cholecystokinin, and epidermal and basic fibroblast growth factors for Parkinson's disease
US6528097Nov 20, 2000Mar 4, 2003The United States Of America As Represented By The Secretary Of The ArmySustained release non-steroidal, anti-inflammatory and lidocaine PLGA microspheres
US6565875Aug 21, 2001May 20, 2003Southern Research InstituteMicrocapsules for administration of neuroactive agents
US6699491Sep 27, 2002Mar 2, 2004Advanced Research And Technology Institute, Inc.Method for modulating glutamate and/or aspartate release in a central nervous system locus
US6844010Jul 18, 2000Jan 18, 2005The United States Of America As Represented By The Secretary Of The ArmyForming burst free, sustained, programmable release micro-capsules; dissolving active material and blend of glycolide-lactide polymers in methylene chloride; converting to water-oil-water emulsion; removing solvent and lyophilizing
US6855331Jun 10, 2002Feb 15, 2005The United States Of America As Represented By The Secretary Of The ArmySustained release hydrophobic bioactive PLGA microspheres
US6902743Apr 6, 1998Jun 7, 2005The United States Of America As Represented By The Secretary Of The ArmyFor immunization against enterotoxigenic escherichia; immunotherapy; sustained release; immunoassay
US6939546Jan 26, 1998Sep 6, 2005The United States Of America As Represented By The Secretary Of The ArmyModel for testing immunogenicity of peptides
US7033608Jun 22, 1999Apr 25, 2006The United States Of America As Represented By The Secretary Of The ArmyMethod of making to form a core of polypeptide or other biologically active agent encapsulated in a matrix of poly(lactide/glycolide) copolymer as a blend of uncapped and end-capped forms
US7229635Apr 20, 2001Jun 12, 2007Indiana University Research And Technology CorporationPharmacotherapeutic process and composition for central nervous system disorders
US7309232Oct 10, 2003Dec 18, 2007Dentigenix Inc.Methods for treating dental conditions using tissue scaffolds
US7374782Oct 25, 2001May 20, 2008Baxter International Inc.Inhaler; supplying therapy to lungs
US7537787Jan 8, 2004May 26, 2009Indiana University Research And Technology Corporationproviding prolonged release of thyrotropin-releasing hormone in situ at the central nervous system locus over a period of time by in situ stereotaxic implantation
US7604811Dec 10, 1996Oct 20, 2009The United States Of America As Represented By The Secretary Of The ArmyInducing an immune response in mammals comprising administering an antigenic synthetic peptide containing Colonization FactorAntigen/I pilus protein T-cell epitopes encapsulated within a biodegradable matrix of glycolic acid-lactic acid copolymer; amino acid sequences; intestinal bioavailability
US7815941May 12, 2005Oct 19, 2010Baxter Healthcare S.A.prepared by dissolving compounds containg nucleic acids in a suitable solvent or solvent system and forming microspheres from the resulting solution; use in treatment of autoimmune diseases
US7884085May 12, 2005Feb 8, 2011Baxter International Inc.Delivery of AS-oligonucleotide microspheres to induce dendritic cell tolerance for the treatment of autoimmune type 1 diabetes
US7964574Aug 6, 2007Jun 21, 2011Baxter International Inc.Microsphere-based composition for preventing and/or reversing new-onset autoimmune diabetes
US8022046Apr 20, 2009Sep 20, 2011Baxter International, Inc.Microsphere-based composition for preventing and/or reversing new-onset autoimmune diabetes
US8075919Jul 19, 2004Dec 13, 2011Baxter International Inc.Methods for fabrication, uses and compositions of small spherical particles prepared by controlled phase separation
US8323615Aug 20, 2008Dec 4, 2012Baxter International Inc.Methods of processing multi-phasic dispersions
US8323685Aug 20, 2008Dec 4, 2012Baxter International Inc.Methods of processing compositions containing microparticles
US8333995May 12, 2005Dec 18, 2012Baxter International, Inc.Protein microspheres having injectable properties at high concentrations
US8367427Aug 20, 2008Feb 5, 2013Baxter International Inc.Methods of processing compositions containing microparticles
US8389493May 9, 2011Mar 5, 2013Baxter International Inc.Microsphere-based composition for preventing and/or reversing new-onset autoimmune diabetes
US8529928Jul 6, 2007Sep 10, 2013Georgia Tech Research CorporationBiomimetic polymers and uses thereof
US8728525Nov 7, 2006May 20, 2014Baxter International Inc.Protein microspheres retaining pharmacokinetic and pharmacodynamic properties
USRE40786Jun 2, 2000Jun 23, 2009The United States Of America As Represented By The Secretary Of The ArmyIMMUNOSTIMULAnts COMPOSITION COMPRISING IMMUNOGENIC SUBSTANCE ENCAPSULATED IN POLYLACTIDE-CO-GLYCOLIDE MATRIX; vaccine for HIV-1
USRE41157Nov 30, 1999Mar 2, 2010The United States Of America As Represented By The Secretary Of The ArmyMicroparticle carriers of maximal uptake capacity by both M cells and non-M cells
CN100462105COct 19, 2006Feb 18, 2009中国人民解放军第四军医大学Method for preparing recombinant neuro surrogate
EP2072040A1May 12, 2005Jun 24, 2009Baxter International Inc.Therapeutic use of nucleic acid micropheres
EP2335689A1May 12, 2005Jun 22, 2011Baxter International Inc.Method of manufacturing nucleic acid micropheres
EP2647712A2Aug 6, 2007Oct 9, 2013Baxter International IncMicrosphere-based composition for preventing and/or reversing new-onset autoimmune diabetes
WO1998010775A1 *Sep 16, 1997Mar 19, 1998Stephen F BadylakComposition and method for repairing neurological tissue
WO1999052708A1Apr 13, 1999Oct 21, 1999Luminex CorpLiquid labeling with fluorescent microparticles
WO2006047299A2 *Oct 21, 2005May 4, 2006Sean M KearnsOrganotypic slice cultures and uses thereof
WO2006097725A2 *Mar 15, 2006Sep 21, 2006Queen Mary & Westfield CollegePharmaceutical compositions comprising microparticles for delivery into neurons
WO2008006064A2 *Jul 6, 2007Jan 10, 2008Georgia Tech Res InstBiomimetic polymers and uses thereof
WO2009158724A2 *Jun 29, 2009Dec 30, 2009Tepha, Inc.Improved injectable delivery of microparticles and compositions therefore
WO2010014021A1Jul 30, 2009Feb 4, 2010Mesynthes LimitedTissue scaffolds derived from forestomach extracellular matrix
Classifications
U.S. Classification424/426, 424/425, 424/423, 424/424, 424/496, 424/451, 424/497, 514/963, 424/490
International ClassificationA61P25/28, A61K9/00, A61K9/52, A61P25/14, A61P25/00, A61P25/08, A61K9/16, A61K47/34, A61K31/135, A61K31/137, A61P25/16, A61K47/30
Cooperative ClassificationY10S514/963, A61K9/1647, A61K9/0085, A61K31/135
European ClassificationA61K9/16H6D4, A61K9/00M22, A61K31/135
Legal Events
DateCodeEventDescription
Jul 2, 2007ASAssignment
Owner name: BROOKWOOD PHARMACEUTICALS, INC., ALABAMA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SOUTHERN RESEARCH INSTITUTE;REEL/FRAME:019508/0335
Effective date: 20070628
Apr 28, 2006FPAYFee payment
Year of fee payment: 12
Apr 5, 2002FPAYFee payment
Year of fee payment: 8
Apr 15, 1998FPAYFee payment
Year of fee payment: 4